How to write a database to a text file in android

Question

I am working on a Spying application for my college project purpose. For that i have logged the Calls, Location and SMS of the device and stored them in a database. Now i want to export the contents of the database to a text file.. I tried the below code.

private void readAndWriteCallsData() {

    File dataBaseFile = getDatabasePath("DATABASE"); 

    File callDataFile = new File(Environment.getDataDirectory()+"/data/com.example.myapp/databases/"+"DATABASE");

    try {

        BufferedReader dbFileReader = new BufferedReader(new FileReader(callDataFile));

        String eachLine;

        while((eachLine = dbFileReader.readLine()) != null)
        {

                Callslog.append(eachLine);
                Callslog.append("\n");

        }

    } catch (IOException e) {

        e.printStackTrace();
    }


}

But that is not working... Please help me...

Answer 1

You can encode the database file from binary stream to character stream by Base64, then decode the text when nessesary.

First find a Base64 library. You can use http://sourceforge.net/projects/iharder/files/base64/. There's only one file, "Base64.java".

Code example:

private void readAndWriteCallsData() {
    File callDataFile = new File(Environment.getDataDirectory()+"/data/com.example.myapp/databases/"+"DATABASE");
    try {
        FileInputStream fis = new FileInputStream(callDataFile);
        try{
            byte[] buf = new byte[512];
            int len;
            while((len = fis.read(buf)) > 0){
                String text = Base64.encodeBytes(buf, 0, len); // encode binary to text
                Callslog.append(text);
                Callslog.append("\n");
            }
        }finally{
            fis.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

To revert it, code like following:

private void revertCallsData() {
    File encodedCallDataFile; // get reference to the encoded text file
    try {
        BufferedReader br = new BufferedReader(new FileReader(encodedCallDataFile));
        try{
            String line;
            while((line = br.readLine()) != null){
                byte[] bin = Base64.decode(line); // decode each line to binary, you can get the original database file
            }
        }finally{
            br.close();
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
}

Answer 2

ok guys after a lot of hit and trial i finally found the solution, here is the code, i saved the functionality in a button.

final String SAMPLE_DB_NAME = "MyDBName.db";//database name
save.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                    File sd = Environment.getExternalStorageDirectory();
                    File data = Environment.getDataDirectory();
                    FileChannel source=null;
                    FileChannel destination=null;
                    String currentDBPath = "/data/"+ "your package name" +"/databases/"+SAMPLE_DB_NAME;
                    String backupDBPath = SAMPLE_DB_NAME;
                    File currentDB = new File(data, currentDBPath);
                    File backupDB = new File(sd, backupDBPath);
                    try {
                        source = new FileInputStream(currentDB).getChannel();
                        destination = new FileOutputStream(backupDB).getChannel();
                        destination.transferFrom(source, 0, source.size());
                        source.close();
                        destination.close();
                        Toast.makeText(getApplicationContext(),"Your database has been exported",
                                Toast.LENGTH_LONG).show();
                    } catch(IOException e) {
                        e.printStackTrace();
                    }


            }


        });

the database will be saved in /storage/emulated/0/

Answer 3

I would recommend to export into a structered file format such as JSON or CSV. Here is my JSON exporter method. Maybe it helps

private static final String LOG_FOLDER = "/ExportFolder";
private static final String FILE_NAME = "export_file.json";

public static void exportMeasurementsJSON(Handler mHandler) {

    sendToastMessage("Export to JSON started", mHandler);

    File folder = new File(Environment.getExternalStorageDirectory()
            + LOG_FOLDER);
    if (!folder.exists())
        folder.mkdir();

    final String filename = folder.toString() + "/"
            + getLogFileName(".json");

    try {
        FileWriter fw = new FileWriter(filename, false /* append */);

        // get the db
        SomeDateSource db = PIApplication.getDB();

        // Google Gson for serializing Java Objects into JSON
        Gson mGson = new GsonBuilder().create();

        Cursor c = db.getAllRows();
        if (c != null) {
            while (c.moveToNext()) {
                fw.append(mGson.toJson(new DBEntry(c
                        .getString(1), c.getString(2), c
                        .getDouble(3), c.getLong(4))));
                fw.append('\n');
            }
            c.close();
        }
        fw.close();
        sendToastMessage("Export finished", mHandler);

    } catch (Exception e) {
        sendToastMessage("Something went wrong", mHandler);
        e.printStackTrace();
    }   
}

If you're interested I can also add my CSV exporter.